Ignition distributors



July 29, 1969 N. A. JUKES 3,457,905

IGNITION DISTRIBUTORS Filed July 27, 1967 x3 4: H 2' \6 E 23m r 04 5a 22E? a 27 24 :3 t; 3|

:1 a gg L- FIG! 53 II .I v 8 H! II H 5 IO I HII-I United States Patent M3,457,905 IGNITION DISTRIBUTORS Norman Alfred Jukes, Walsall, England,assignor to Joseph Lucas (Industries) Limited, Birmingham, England FiledJuly 27, 1967, er. No. 656,585 Claims priority, application GreatBritain, Aug. 19, 1966, 37,250/66 Int. Cl. F02p 5/02, 5/10 US. Cl.123-117 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates toignition distributors for road vehicles, of the kind comprising acasing, a rotatable shaft extending within the casing and carrying thedistributor arm and a contact breaker assembly supported Within thecasing for angular movement relative to said shaft, and including afixed contact and a movable contact, said movable contact being movableinto and out of engagement with said fixed contact in response torotation of said shaft.

According to the invention a distributor of the kind specified includesa first vacuum unit slidably supported on the casing, a second vacuumunit secured to the casing, means interconnecting the first and secondvacuum units so that operation of the second vacuum unit causes slidingmovement of the first vacuum unit relative to the casing, further meansinterconnecting the first vacuum unit and the contact breaker assemblyso that operation of the first vacuum unit while the second vacuum unitis at rest moves the assembly angularly from a zero position, which itoccupies when both the first and the second vacuum units are at rest, ina direction to advance the ignition timing of the distributor andoperation of the second vacuum unit while the first vacuum unit is atrest moves the contact breaker assembly, through the first vacuum unitand said further means, angularly from said zero position in a directionto retard the ignition timing of the distributor.

The invention further resides in an ignition timing system utilizingignition distributor as specfied in the preceding paragraph.

One example of the invention is illustrated in the accompanying drawingswherein:

FIGURE 1 is a partly diagrammatic representation of a distributor andits associated ignition timing system, and

FIGURE 2 is a sectional view of the distributor shown in FIGURE 1.

Referring to the drawings, the distributor includes a casing havingrotatable therein an axially extending shaft 11 the periphery of whichis shaped to define a cam surface 12. Surrounding the shaft 11 andsupported for angular movement relative thereto is an annular plate 13.The plate 13 carries the fixed and movable contacts 14, 15 of thedistributor, the movable contact 15 having a cam follower 16 associatedtherewith. The cam follower 16 engages the cam surface 12, rotation ofthe shaft 11 serving to open and close the contacts 14, 15 and angular3,457,905 Patented July 29, 1969 movement of the plate 13 serving toadjust the timing of the distributor in known manner.

A first vacuum unit 17 is mounted on the casing for sliding movement andthe diaphragm 18 of unit 17 is connected to the plate 13 by a link 19,conveniently in the form of a tension spring.

A push rod 21 is slidably received in the casing 10 and extends betweenthe body of the unit 17 and the diaphragm 23 of a second vacuum unit 22,the unit 22 being secured to the casing 10 and the arrangement beingsuch that movement of the diaphragm 23 is transmitted to the unit 17through the rod 21.

The unit 17 is connected by way of a conduit 24 to the air inlet side ofa carburetor 25 near to the throttle butterfly valve 26 thereof and byway of a conduit 27 to a two position spool valve 28, the unit 22 beingconnected by way of a further conduit 29 to the valve 28.

The valve 28 serves in the first position of the spool to close theconduit 27 and to connect the conduit 29 to atmosphere, and in thesecond position of the spool to connect the conduit 27 to atmosphere andto connect the conduit 29 to the engine manifold side of the carburetor.

During normal running of the engine the throttle butterfly valve 26 isopen and the valve 28 is in its first position. Thus the unit 22 is inits rest position, both sides of the diaphragm 23 being subjected toatmospheric pressure and the rod 21 and consequently the unit 17 beingin their extreme right hand positions as seen in the drawings. The unit17, is however, subject to the depression at the air inlet side of thecarburetor and changes in this depression serve to move the plate 13,through the intermediary of the diaphragm 18 and the link 19, from thezero position it occupies when both the units 17 and 22 are in theirrest position, in a direction to advance the timing of the engine,return movement of the plate 13 towards its zero position beingaccomplished by a spring 18a acting on the diaphragm 18.

When the throttle butterfly valve 26 is closed, the spool of the valve28 is moved to its second position, and owing to the closure of thevalve 26 a high depression exists at the engine manifold side of thecarburetor. The unit 17 returns to its rest position, since both sidesof the diaphragm 18 are now open to atmosphere and the plate 13 isreturned to its zero position. However, the unit 22 is subjected to thehigh depression at the engine manifold side of the carburetor 25 and theunit 17 is moved to the left by movement of the diaphragm 23. Thismovement serves through the link 19 to move the plate 13 from its zeroposition in a direction of retard to timing of the engine. Returnmovement of the plate 13 from its retarded position to its zero positionis effected by a spring 23a acting on the diaphragm 23.

The spool of the valve 28 is moved either through a mechanical linkage31 associated with the accelerator pedal of the vehicle or by apneumatic linkage 32 (shown in dotted lines in FIGURE 1) responsive tothe engine manifold depression.

The ignition system previously described is used in a vehicle havingexhaust emission control. It is known that when internal combustionengines are run with their throttle valves closed, for example whenidling or during overrun, incomplete combustion of the fuel entering theengine takes place and there is conseqently a high percentage ofnoxious, unburnt, hydro-carbons in the exhaust products of the engine.In order to minimise the amount of unburnt hydro-carbons in the exhaustproducts it has been proposed to provide means 33 for allowing extra airto enter the engine 34 during closed throttle conditions to ensurecomplete combustion of the fuel. However, this more efiicient combustionof the fuel leads to an increase in engine speed which is undesirableboth during idling and overrun conditions. The use of the systerndescribed ensures that during closed throttle conditions the increase inengine speed due to the more efiicient combustion is negated byretarding the ignition of the engine.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. An ignition distributor, for a road vehicle, including a casing, ashaft mounted for rotation in the casing, a distributor arm carried bysaid shaft, a contact breaker assembly operable in response to rotationof said shaft and mounted within the casing for angular movementrelative to said shaft, angular movement of the contact breaker assemblyrelative to said shaft varying the ignition timing of the distributor, afirst vacuum unit secured to said casing, a second vacuum unit mountedfor sliding movement on the casing, first connecting means operativelyconnecting said second vacuum unit to said contact breaker assembly,whereby operation of the second vacuum unit, while the second vacuumunit is stationary relative to said casing, moves the contact breakerassembly in a first direction, second connecting means operativelyconnecting the first vacuum unit to the second vacuum unit wherebyoperation of the first vacuum unit while the second vacuum unit isinoperative moves the contact breaker assembly, through the secondvacuum unit and the first connecting means in a direction opposite tosaid first direction, said contact breaker assembly having a zeroposition which it occupies when both the first and th second vacuumunits are inoperative, and movement of said contact breaker assembly insaid first direction from said zero position serving to advance theignition timing of the distributor while movement of said contactbreaker assembly in said opposite direction from said zero positionretards the ignition timing of the distributor.

2. An ignition distributor as claimed in claim 1 in combination with aninlet manifold, an associated throttle valve, and a valve means to forman ignition timing system, the valve means movable from a first positionwhich it occupies during normal running of the engine of the vehicle,and in which it serves to connect the first vacuum unit to the inletmanifold of the engine, and to connect the second vacuum unit toatmosphere so that variations in the manifold depression during normalrunning serve through the first vacuum unit to advance the ignitiontiming of the distributor from said zero position, to a second positionwhich it occupies 4 when the engine is running with its throttle valveclosed and in which the valve means serves to connect the first vacuumunit to atmosphere and to connect the second vacuum unit to the inletmanifold, so that the high depression which occurs in the manifold whenthe engine is running with its throttle valve closed is utilized toretard the ignition timing of the distributor from said zero position.

3. A combination as claimed in claim 2 wherein said valve means isoperatively connected to the throttle valve of the engine so that as thethrottle valve is moved from an open position to a closed position saidvalve means is moved from its first position to its second position, andas the throttle valve is moved from a closed position to an openposition said valve means is moved from its second position to its firstposition.

4. A combination as claimed in claim 2 wherein said valve means isoperatively connected to the inlet mani fold of the engine so that whenthe depression in the manifold rises above a predetermined value saidvalve means is moved from its first to its second position and When thedepression in the manifold falls below a predetermined value said valvemeans is moved from its second to its first position.

5. A combination as claimed in claim 2 further in combination with aninternal combustion engine having means for allowing extra air to enterthe engine during closed throttle conditions, to ensure substantiallycomplete combustion of the fuel entering the engine.

References Cited UNITED STATES PATENTS 2,091,924 8/1937 Harmon 123-117.12,557,527 6/1951 Colvin et al. 123-117.1 2,731,523 l/l956 Downing123-117.1 3,027,884 4/1962 Bale. 3,272,191 9/1966 Walker 123-117.1

FOREIGN PATENTS 616,940 8/1935 Germany.

WENDELL E. BURNS, Primary Examiner US. Cl. X.R. 123-97

